Description is given with reference to FIG. 1 of a general configuration of an inspection to be conducted on a printed circuit board. An inspection jig 1 is disposed between a printed circuit board to be inspected and an inspection device, so as to ensure conduction and allow inspection to be conducted regarding electrical properties such as a resistance value. A contact holder 30 and an electrode section 40 are connected with the inspection device by means of a connector 45. The contact holder 30 is configured to hold a plurality of contacts 10 that are adapted to conductively contact inspection terminals of the printed circuit board to be inspected. The electrode section 40 has electrodes and is configured to detachably support the contact holder 30 to establish conductive contact of the electrodes with the contacts 10. The configuration allowing separation of the contact holder 30 and the electrode section 40 is effective for fabrication and maintenance.
Background art includes a perpendicular coil spring probe of Patent Document 1 wherein an attempt is made to improve direct current resistance and inductance (an alternate current resistance property) of the internal resistance of the probe, and a first embodiment thereof is depicted in FIG. 5. The probe includes an upper probe pin 100, a compression coil spring 400, a guide tube 300, and a lower probe pin 200, and the upper probe pin is contained in the guide tube, such that an attempt is made to improve the internal resistance. The number of component is however four and thus there is still room for cost reduction.
FIGS. 2, 3, and 4 of Patent Document 2 include a longitudinal cross-sectional view and an enlarged view of a contact pin portion of a test head that includes a contact pin (reference numeral 1 of Document 2), a coil spring (reference numeral S of Document 2), and a receiver pin (reference numeral 3 of Document 2). The number of components is three and, as in Patent Document 1, an attempt is made to improve the internal resistance by housing the contact pin in the receiver pin; however, with smaller dimensions of the components, processing an insertion hole (reference numeral 34 of Document 2) in the receiver pin is not easy.
FIG. 1 of Patent Document 3 depicts a perpendicular spring probe with two components, i.e., a contact pin (reference numeral 100A of Document 3) and a tubular body (reference numeral 200A of the document). A spring (reference numeral 230A of Document 3) is provided in a middle portion of the tubular body and a contact pin is contained in the tubular body, such that an attempt is made to improve the internal resistance. This configuration however involves higher cost because of additional provision of a conical connection cap (reference numeral 240B of the document) to the tubular body for reducing contact resistance. Non-use of a connection cap may increase the area of contact and hence invite connection failure due to insufficient contact pressure under a lower load condition.
FIG. 2 of Patent Document 4 depicts a contact including a bar-shaped member (reference numeral 21 of Document 4), a coil spring (reference numeral 23 of Document 4), and a connection terminal (reference numeral 24 of Document 4). The number of components is three, and the connection terminal has a tapered second end, such that even a small electrode is contacted therewith. The tapered shape is however not conical, and the contact condition is thus not certain, which may involve a higher level of skill in design to define the electrode area, load, and specifications for processing.
As described above, elaboration is made in various manners on conductive contact between the electrode of the electrode section 40 and the contact 10 of the inspection jig 1 and on the internal electrical properties of the contact 10, but there is still room for improvement.